How would you find the magnetic force on a piece of metal by an electromagnet?

Click For Summary

Discussion Overview

The discussion revolves around calculating the magnetic force exerted by an electromagnet on a piece of metal, particularly focusing on the factors influencing this force, such as the properties of the metal and the magnetic field strength. The context includes theoretical and practical considerations related to electromagnet design and application.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant questions whether the type of metal being attracted affects the magnetic force and seeks methods to calculate the force based on field strength.
  • Another participant explains that the magnetic properties of the metal are crucial in calculations and mentions that air gaps, including layers of paint or rust, significantly affect field strength.
  • It is noted that the force of attraction is proportional to the square of the field strength at the electromagnet's face, with a specific example stating that one Tesla corresponds to a pull force of 58 pounds per square inch of pole area.
  • A later reply raises concerns about the assumptions underlying this relationship, particularly regarding the geometry of the magnet and substrate, suggesting that the calculations may depend on specific conditions.
  • One participant mentions using FEMM (Finite Element Method Magnetics) to analyze the situation, indicating a practical approach to solving the problem.

Areas of Agreement / Disagreement

Participants express varying views on the factors affecting the magnetic force, with no consensus reached on the assumptions necessary for accurate calculations. The discussion remains unresolved regarding the specific conditions under which the stated relationships hold true.

Contextual Notes

Participants highlight limitations related to assumptions about the geometry of the electromagnet and the substrate, as well as the influence of air gaps on field strength. These factors remain unresolved in the discussion.

breadandbacon
Messages
2
Reaction score
0
Does the metal being attracted make a difference?
How would you find the force on the metal knowing the field strength there?
How would you even calculate the field strength of an electromagnet with a core? In my case, it is one of those junkyard electromagnets.
thanks
 
Physics news on Phys.org
When you grab something with an electromagnet, you are making a magnetic circuit. To learn how to calculate, search magnetic circuit. The magnetic properties of the metal being attracted are part of the calculation. Keep in mind that the field strength is strongly affected by any air gaps, and that a layer of paint or rust is an air gap.

The force of attraction is proportional to the square of the field strength at the face of the electromagnet where it contacts the metal. A field strength of one Tesla has a pull force of 58 pounds per square inch of pole area.
 
  • Like
  • Informative
Likes   Reactions: hutchphd, breadandbacon and anorlunda
jrmichler said:
The force of attraction is proportional to the square of the field strength at the face of the electromagnet where it contacts the metal. A field strength of one Tesla has a pull force of 58 pounds per square inch of pole area.
A useful number...there must be some assumption about the rest of the geometry, though? I am guessing this is for a "long" magnet with flat pole on a semi-infinite substrate??Any assumptions about substrate (obviously ferromagnetic I guess) but does it somehow not matter?I would find this a very useful thing to know but don't understand when to apply it. Thanks
 
yall i ended up just using FEMM and it worked out fine
 

Similar threads

  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 17 ·
Replies
17
Views
4K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 14 ·
Replies
14
Views
4K
  • · Replies 14 ·
Replies
14
Views
2K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 16 ·
Replies
16
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K